Method for measuring corrosion inhibitor concentration

Abstract

A method for measuring metal ion concentration includes the following steps of: providing a measuring solution having a corrosion inhibitor; adding a specific quantity of metal ion solution into the measuring solution; providing a potential scan device ( 1 ); measuring a cyclic voltammetry curve of the measuring solution using the potential scan device at a constant scan rate in a specific potential range, the cyclic voltammetry curve has a peak current; obtaining a linear equation, which indicates a linear relationship of peak current versus a concentration of corrosion inhibitor in standard corrosion inhibitor solution in the specific potential range, the peak current is a peak current of cyclic voltammetry curve of the specific quantity of metal ion solution metal ion in the standard corrosion inhibitor solution in the specific potential range; and determining a concentration of the corrosion inhibitor of the measuring solution by computing the peak current of the cyclic voltammetry curve of the measuring solution in linear equation.

1 . A method for measuring corrosion inhibitor concentration comprising the steps of: 
 providing a measuring solution having a corrosion inhibitor;    adding a specific quantity of metal ion solution into the measuring solution;    providing a potential scan device;    measuring a cyclic voltammetry curve of the measuring solution using the potential scan device at a constant scan rate in a specific potential range, the cyclic voltammetry curve has a peak current;    obtaining a linear equation, which indicates a linear relationship of peak current versus a concentration of corrosion inhibitor in standard corrosion inhibitor solution in the specific potential range, the peak current is a peak current of cyclic voltammetry curve of the specific quantity of metal ion solution metal ion in the standard corrosion inhibitor solution in the specific potential range; and    determining a concentration of the corrosion inhibitor of the measuring solution by computing the peak current of the cyclic voltammetry curve of the measuring solution in linear equation.    
   
   
       2 . The method for measuring corrosion inhibitor concentration as claimed in  claim 1 , wherein a determination of the linear equation comprises the steps of: providing a plurality of groups of standard corrosion inhibitor solutions, in which the corrosion inhibitor concentration is known; providing a plurality of groups of the specific quantity of metal ion solutions; adding the specific quantity of metal ion solution into a corresponding standard corrosion inhibitor solution; measuring a cyclic voltammetry curve of each group of standard corrosion inhibitor solution using the potential scan device at the constant scan rate in the specific potential range, the cyclic voltammetry curve having a peak current; determining the linear equation base on the corrosion inhibitor concentration of the standard corrosion inhibitor solution and the corresponding peak current.  
   
   
       3 . The method for measuring corrosion inhibitor concentration as claimed in  claim 2 , wherein the metal ion is selected from the groups consisting of nickel ion, copper ion, chromic ion, and ferrous ion.  
   
   
       4 . The method for measuring corrosion inhibitor concentration as claimed in  claim 2 , wherein metal ion is copper ion.  
   
   
       5 . The method for measuring corrosion inhibitor concentration as claimed in  claim 4 , wherein the concentration of the metal ion is 0.001 mol/l.  
   
   
       6 . The method for measuring corrosion inhibitor concentration as claimed in  claim 1 , wherein a PH value of the measuring solution and the reference metal ion solutions is in the range from 3.0 to 4.0.  
   
   
       7 . The method for measuring corrosion inhibitor concentration as claimed in  claim 1 , wherein the constant scan rate is 0.1 volts/s.  
   
   
       8 . The method for measuring corrosion inhibitor concentration as claimed in  claim 1 , wherein the specific potential range is from 0.4 to −0.4 volts.  
   
   
       9 . The method for measuring corrosion inhibitor concentration as claimed in  claim 1 , wherein the potential scan device includes a potentiostat, and a potential-current recorder electrically connected with the potentiostat.  
   
   
       10 . The method for measuring corrosion inhibitor concentration as claimed in  claim 9 , wherein the potentiostac includes a working electrode, auxiliary electrode, and a reference electrode.  
   
   
       11 . The method for measuring corrosion inhibitor concentration as claimed in  claim 10 , wherein the working electrode is glass carbon electrode, the auxiliary electrode is platinum electrode, the reference electrode is silver-chloride.